Transducer



Nov. 24, 1964 R. J. PULKRABEK TRANSDUCER 2 Sheets-Sheet 1 Filed March 14 1962 INVENTOR /Qnuw fz M1485:

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NOV- 24, 1964 R. J. PULKRABEK 3,158847 TRANSDUCER Filed March 14 1962 2 SheetS-Sheet 2 FIE. E

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4rroRmsYs United States Patent O 3,l58,847 TRANSEUCER A lph J. Pulkrahek, Minneapolis, Miran., assignor, by mesne assignxnents, to Data Products Corporation, Cnlver City, Calif., a eorporation of Bel-aware Filed Mar. 14, 1952, Ser. No. 1719,71'6 6 Claims. ({Ji. 34il-17 .1)

This invention relates generally to transducers and is more particularly directed to transducers useful in providing information interchange between a moving storage medium and devices and apparatus for utilizing and generating such information.

An example of one application wherein the subject invention may be utilized is that concerned with the storing and retrieval of information utilized in the operation of the familiar computer in which an immense number of bits of information must be transferred to and from a storage medium. T his, of necessity, has required the use of apparatns requiring dynamic interchange of information at a reasonably rapid rate. As a specific example, one form of equipment utilized for storage of information may be described as a disc file in which a plurality of discs of magnetizable storage medium are c used to rotate at relatively high speeds With accompanying high rotational and linear velocities. The greater the rate at which such information is dynamically interchanged, the greater the necessity for relatively close magnetic conpling between the information exchanging transducers and the magnetic storage medium.

Unfortunately, it is dificult to provide a magnefic medium for such storage which presents an absolutely smooth surface to any transducers which may be utilized for this purpose. Tl'r's factor has resulted in the use of what may be described as the iying Wing type of transducer in which the transducer is supported on top of a moving film of air associated with the motion of the storage medium. Generahy spealdng, the greater the motion the greater the distance the transducer will lie from the storage medium unless some biasing force is utilized to overcome some of the buoyant force from the moving film of In overcoming the buoyant force of the moi ng filrn of air, it will be appreciated that the distance between the surface of the transducer and that of the moving magnetic storage media becomes very small. In fact, it 'oecomes less than the normal surface in perfections which ale present in substantially 8"' forms of magnetic storage medium.

U 7ess some means is provided for allowing the surface of the transducer to conform to the constantly changing surface of the magnetic storage media, severe daniage due to actual physical contact het 'cen the transducer and the media results in rapid wear and deterioration; and in some cases, virtual destruction of the equipment.

One example of a transducer for use with moving magnetic stor. e media may be found inra certain co-pending patent application, Serial No. 142,793, filed Octoher 4, the names of Wallace W. loslie, .Donald K. Sampson and Byron D. Smith and assigned to the assignee of the present application.V

The present invention overcomes a primarydifficulty arising with the use of prior art devices and ap'paratus for the dynamic transfer of information. It has been discovered that a tri-axial degree of freedom of motion of' the transducer surface to be positioned in proairnity to the storage medium is ulmecessary and that the combination "ice of certain elements associated with the transducing apparatus which is the subject matter of the present invention results in an improved performance with regard to reliability and fidelity of transfer of information while allowing a su'ostantial Variation in manufacturing tolerances and providing a substantial decrease in cost relaive to the improved response of the transducer to Variatons in the surface of the magnetic storage medium.

The combination of a plurality of pivot points positioned in suitable axial relationship with a transducer can'ying member and the elimination of a substantial amount of n ertial mass which accompanies such configuration, whl, as described below, provide a vastly improved apparatus.

it is therefore an object of the present invention to provide an improved transducing apparatos for use in the dynamic interchange of information between input and output utilization devices and a storage medium.

lt is a further object of the present invention to provide an improved transducer mounting which may be economically Produced.

t is another obect of the present invention to provide a ln'gh compliant transducer mounting for use with dynamic transfer of 1ormation for use With moving storage media.

These and other more detailed and specific objects will be disclosed in the course of the following specification, reference being had to the accompanying drawings, in which l is an exploded assembly diagram of a transducer apparatus,

FG. 2 is'a top View with the cover plate removed and,

PIG. 3 is a sectional view taken along section lines r 3-3 on FiG. 2.

Referrhrg now to the drawings in which like elements are provided with like reference characters, there is shown a transducer carrying member assembly 1% having laterally disposed transdncer carrying portions 12 and 13 into which transducer assemblies zt and 33. are inserted and and securely herld. A typicai transducer assembly is indicated by reference numeral 3h includes an erase coil E8 having a suitable core and a pair of spacers 23 and 21% mounted on either side of the coil. A pole piece 2% is positioned intermediate a read-write coil 22 having appropriate core and is separated from the erase coil and read-write coil by spacer members iti and 21. The transducer carrying member, which may also be described as a pad, is provided with a member, 11 extending normal to the surface of the pad which is normally in proimity to moving storage medium. A pivot bali 14 is placed on the member 11 and a further member 15, adapted to be connected to a connecting member (to be described bel w) is fixedly attached to member 11 through suitable attaching means (not shown). A spring biasing means 4G of substantia'lly U-shape and having a bifurcated portion which islformed to accept a pin member 45 is attached to housing member 16 at the'location shown through the use of rivets ii and 51. A connector mer her which might also-'be considered as a-spring linkage for connection between portion 15 on the transduce'r carrying member iii and the bifurcated end of spring biasing tion ES respectively. m-intain a'snbstantially fiuid tight relationship With hous- .leftredge the 'trfillsducer moun upon a movable arm which may be positioned Vwith 'respect to a moving storage medium in accordance witha predetermined pattern according to the method of recording utilized insofar as the positioning of the information on the recording media isrconcerned.

Appropriate mounting hole-s are provided for the luse of suitable fasteners and it is assumed that the arm for carrying the assembly has an aperture of vsuitable Shape to coact with the end of housing 16 to provide a substantially fluid tight connection.

As is more distinctly shown on PIG. 3, the transdueer carrying member assembly 1% is mounted so as to pro,- vide reciprocating motion .m an upward and downward -irection and is further adapted to rotate about a first pivot point A with respect to the second pivot point shown on the ends of biasing means 4*". The motion of the tl 'i d pivot point B is described by the dotted arc. Shown in'dotted Outline is the extended information transferring position of assernbly 19 when the :interior of the housing has been connected to a suitable/'source of fluid under pressure. Suitable manufacturing tolerances are provided so that the diameter of the intermediate spheri- Vtrolled by the relative magnitudes of the forces involved.

It may be recognized that the application of a compressible fluid under pressure'results in a relatively constant spring rate Withrregard'to'the downward force applied .to transducer memberassernbly 1d and that the assembly is able to move in a reciprocating upward and downward directiomwith respect to the sense of the drawings, in a relatively free manner.l Should the source of como pressibie fluid under pressure fail, it will .be seen that the force exerted by spring member 4h is .such that it'wiil move the transducer carrying assembly li) 'in an upward direction away from the moving storage medium.

An inspection of the manner in which the member is connected to the biasing means 4h through connecting mems 47 will show that the lateral rotational movement `ofithe transducer carriing assernbly 1G is constrained. Motion about a lateral horizontal axis Vis restrained by the bifurcated portions 41 and 'fr-2V atone entremity of Vthe spring biasing means 4d. It may also bevnoted that each of the bifurcated end portions 41 and 42 terminate in sockets 43 and 44 respeotively for the insertion of mounting pin 45. zL'ikewise, the connectingrmeans 47 has a pair'of journals 48 and-? positioned for the reception of mounting pin 46 which also extends through the trans- Vverse opening in member 15. It isv anticipated that the 'connecting member 47 wlll be constructedout of material having a low density or low inertial mass characteristic so as: to allow free movement of transducer carrying assembly 1d about its' pivotV point A. i,

In operation, the transducer is energized from a suitable sour'ce of compressible uid lunderpressure and is positioned at a desirable-location with respectrto a moving 'storage mediumwhich may be assumedto move from left-to' right with'respectv to theficrosssectional view of FIG.3. Movementcof the Jstorage'mediurn creates a iboundary layer, offair which serves to maintaintransducerjcarrying-member 19 ata small distance above' the V: Vstorage medium; Surface imperfections 'caused' through .along its longitudinal axis and `rotational connector means 4-7 willl in turn pivot about pin se-VV cureiy held at the o'ne extremity of spring biasing means it is therefore seen that-aside from the mass of the 49. transducer carrying member assembly 10, the inertia to lbe overcome exists only by virtue of the small connecting means which does not move an appreciable distance.

Thus through the combination of elements described above, the present invention provides a transducer of highlly improved characteristics of operation.

it is understood that suitable modifications may be made in the structure as disclosed, provided such modifications come within the spirit and scope ofV the appended claims. l-laving now therefore fully illustrated and described my invention, What i claim to be new and desire to protest .by Letters Patent is:

1. Apparatus for use in po'sitioning transducers in information transferring relationsllip with a moving storage medium comprilsing; a housing'member including an aperture and a means for supplying the interior of said housing with arcompressble fiud under pressure; a transducer carrying member having a surface to be positioned in proximity to a moving storage medium 'and a further member extending normal to said surface, having an enlarged intermediate spherical portion substantially the i size of said aperture for coacting with said aperture to provide a compressible fluid lubricated piston and pivot and having an end portion positioned within said housing; biasing means positioned within said housing for retracting said transduce'r carrying member :in the absence of fiuid under pressure, said biasing means including `mounting,means for rotatabllyengaging a connecting' means along an .aXis normal to the axis Vof said further member; and 'connecting means interconnecting said biasing means and the end of said further member, said biasing means and said connecting means cooperating to allow reciprocating movement of said further means motion about said spherical enlarged portion. i i

2. The apparatus'offclaim 1 iii-which the' bia'sing ate portion substantially the same size as said aperture, the

center of said enlarged portion forming a first pivot for said transducer mounting; a second pivot mounted within said housing along the axis of said taperture; and connecting means connected-to said second pivot and to a third pivot at the end of said elongated member whereby said third pivot pointris rotatable about said first pivot and allV of said pivots are movable longitudinallyV of the axis of said.

- aperture.

4. The ap'paratus of claimlr3'in which the second and third pivots -cooperate with thetconnecting means torc-V strict rotational movement about l,one axis of movement`- of the transducer rnounting.V i i V35; The apparatus of Vciaim .Sin which the 'connecting manufacturing of the medium and possiblyduelto mechemical vibrations altering the Shape of the medium 'unv;dert'transient conditions arefconstantly encouutered and '1- it'willbe necessary for'thettransducer carrying member i assembly ldto rotate .about point Aandtomove in fa i -reciprocating upv'ardV 'and downward movement. The

ting assetnbly means is comprised of'rnat massratio. li

i 6. Apparatusfor use with a moving storage mediurn`- comprising a hollow-housing positionable inlrpi'oximity to ,g I, said moving storagemcdium,'said=housinghaving an aperpo ture for receivingca trahsduce'r' Vmountingr'i 1ernber', said transducer mounting'memb'er incl'uding a rofdextending`` from'ouftside lsaid hoiising through its aperture into said erial having a: high 'sstrengthV to A U housing, a transducer mounted on the end of said rOd ing one end attached to said housing wall, and means externfl to said housing, a pivot ball having an opening pivgtabiy fmecng the other end of sm'd bifurcated therethrough, said pivot ball fitting over said rod and spring means to said holding member.

being dimensioned for slidably filling the opening in said housing, a terminating member atached to the other end 5 Reerms Clted m the file of thls Patent of said rod With said housing and holding said pivot ball UNITED STATES PATENTS On said rod, a bifurcated spring means in said lmusing hav- 2,3%,651 Vogel May 12, 1959 

1. APPARATUS FOR USE IN POSITIONING TRANSDUCERS IN INFORMATION TRANSFERRING RELATIONSHIP WITH A MOVING STORAGE MEDIUM COMPRISING; A HOUSING MEMBER INCLUDING AN APERTURE AND A MEANS FOR SUPPLYING THE INTERIOR OF SAID HOUSING WITH A COMPRESSIBLE FLUID UNDER PRESSURE; A TRANSDUCER CARRYING MEMBER HAVING A SURFACE TO BE POSITIONED IN PROXIMITY TO A MOVING STORAGE MEDIUM AND A FURTHER MEMBER EXTENDING NORMAL TO SAID SURFACE, HAVING AN ENLARGED INTERMEDIATE SPHERICAL PORTION SUBSTANTIALLY THE SIZE OF SAID APERTURE FOR COACTING WITH SAID APERTURE TO PROVIDE A COMPRESSIBLE FLUID LUBRICATED PISTON AND PIVOT AND HAVING AN END PORTION POSITIONED WITHIN SAID HOUSING; BIASING MEANS POSITIONED WITHIN SAID HOUSING FOR RETRACTING SAID TRANSDUCER CARRYING MEMBER IN THE ABSENCE OF FLUID UNDER PRESSURE, SAID BIASING MEANS INCLUDING MOUNTING MEANS FOR ROTATABLY ENGAGING A CONNECTING MEANS ALONG AN AXIS NORMAL TO THE AXIS OF SAID FURTHER MEMBER; AND CONNECTING MEANS INTERCONNECTING SAID BIASING MEANS AND THE END OF SAID FURTHER MEMBER, SAID BIASING MEANS AND SAID CONNECTING MEANS COOPERATING TO ALLOW RECIPROCATING MOVEMENT OF SAID FURTHER MEANS ALONG ITS LONGITUDINAL AXIS AND ROTATIONAL MOTION ABOUT SAID SPHERICAL ENLARGED PORTION. 